Air ejector augmented compressed air energy storage system

Abstract

Energy is stored in slack demand periods by charging a plurality of underground reservoirs with air to the same peak storage pressure, during peak demand periods throttling the air from one storage reservoir into a gas turbine system at a constant inlet pressure until the air pressure in the reservoir falls to said constant inlet pressure, thereupon permitting air in a second reservoir to flow into said gas turbine system while drawing air from the first reservoir through a variable geometry air ejector and adjusting said variable geometry air ejector, said air flow being essentially at the constant inlet pressure of the gas turbine system.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A method of storing energy during slack demand periods and utilizing said energy in peak demand periods comprising utilizing excess power available during slack demand periods to charge a plurality of underground reservoirs with air to the same peak storage pressure, during peak demand periods throttling the air from one storage reservoir into a gas turbine system at a constant inlet pressure until the air pressure in the reservoir falls to said constant inlet pressure, thereupon permitting air in a second reservoir to flow into said gas turbine system while drawing air from the first reservoir through a variable geometry air ejector and adjusting said variable geometry air ejector, said air flow being essentially at the constant inlet pressure of the gas turbine system. 
     
     
       2. A compressed air energy storage system for use with a gas turbine system operated at a constant inlet pressure comprising a plurality of underground reservoirs, means for charging the reservoirs to the same peak pressure, means for supplying the gas turbine system with air from one of the reservoirs at said constant inlet pressure, means for supplying the gas turbine system with air from a second reservoir when the air pressure of the first reservoir has dropped to said constant inlet pressure including a variable geometry air ejector having a primary inlet connected to the second reservoir and a secondary inlet connected to the first reservoir whereby the pressure in the first cavern is drawn down below said constant inlet pressure, said variable geometry air ejector including therein means for adjusting the total flow rate, the output pressure and the entrainment ratio, whereby flow from the second cavern may be maintained at approximately the constant inlet pressure without a separate throttle.